The restriction enzyme, also known as a restriction endonuclease, is a protein produced by bacteria that slices DNA at a particular site. In other words, it identifies one or some target sequences and cuts DNA at nearly those arrangements. Notably, most restriction enzymes make staggered cuts and produce ends that have single-stranded DNA projections. Nevertheless, some of them create blunt ends. Scientists’ first breakthrough on the road to genetic engineering was fruitful after Herbert Boyer’s efforts on the restriction endonucleases at the University of California. Importantly, these enzymes occur in large numbers of different bacterial classes. Roberts et al. (2014) asserts that they serve as part of the standard defense mechanism that prevents bacterial cells from being invaded by external DNA molecules like those found in viruses. For instance, when a virus attacks a single-celled bacterium, these enzymes are released such that they cut the intruding DNA into little, non-threatening pieces. Most importantly, this nuclease has the aptitude to discriminate between its DNA and the intrusive DNA; else the cell would terminate its own DNA.
The recognition process takes place due to two elements. Firstly, there is two particular nucleotide arrangement (As and Ts, Cs, and Gs). Notably, these sequences act as nuclease targets called restriction sites. Secondly, a shielding chemical signal is present that is placed by the cell on all the aimed course that occurs in its DNA. The signal alters the DNA and averts the nuclease from cutting. As such, the nuclease may chop the invading DNAs that lack protective signal. The restriction enzymes have the extraordinary aptitude to distinguish particular DNA arrangements base pairs-As and Ts, Gs, and Cs. Moreover, they can act as a molecular blade, such that they severe the DNA at just where they detect the sequence of hereditary letters. Restriction enzymes are prevailing because they exist in large numbers and each of them acts in a unique As, Ts, Cs, and Gs sequence.
Area of Use
Restriction enzymes aptitude to reproducibly cut DNA at precise sequences has become a widespread tool used in molecular genetic methods. For instance, these enzymes may be useful to map DNA Genome or fragments. Mapping is the process of determining the genome’s restriction enzyme sites’ order. Notably, the maps create a foundation for further genetic examination. The enzymes are also regularly used in the verification of the distinctiveness of a precise DNA fragment, which is based on the identified restriction enzyme site it encompasses (Nisbet, 2004). One of the essential uses of restriction enzymes is the production of recombinant DNA molecules. These are DNAs that have genes or fragments from two dissimilar organisms. Precisely, the bacterial DNA, which is in the form of a placid, combines with another piece of DNA from a different organism. Restriction enzymes assist at various points in this process.
Restriction enzymes aid in the incorporation of DNA from the trial organism, to prepare the DNA for cloning. Consequently, a bacterial virus or plasmid is digested with an enzyme that produces well-matched ends. These ends may or may not have an overhanging sequence. The DNA from the investigational organism is joined with the plasmid of virus DNA through the use of an enzyme called DNA ligase. As above-mentioned, restriction enzyme digestion verifies the recombinant DNA molecule. Also, these enzymes are applied in the procedures of categorizing individuals or strains of specific species (Shapiro, 1997). For instance, the process of splitting large DNA fragments is referred to as gel electrolysis. Typically, these fragments come from the digestion of a microbial genome that has a rare-cutting restriction enzyme. As such, the process produces reproducible arrangements of DNA bands that aid in distinguishing various bacteria strains. Moreover, they help determines if a widespread disease outbreak emanated from a specific strain.
Discussion
Cloning human beings using the processes mentioned above has received diverse reactions based on ethical considerations. For instance, the cloning of “Dolly,” a sheep cloned from an old sheep’s mammary gland cell nucleus in 1997 was successful; hence, talks about the probability of human cloning being developed. While there have been minimal cases of attempted human cloning, animal cloning has received strong opposition. Bioethical principles demand that before conducting long-standing and methodical research, all possible effects on nature should require proper consideration. Therefore, using animals and plants for cloning research in most cases translate to irresponsible handling of the plants and animals world, not to mention the ecosystem. Thus, in 1986 the Organization of Economic Cooperation and Development (OECD) formulated the Recombinant DNA Safety Considerations and also a couple of recommendations. Hence, these considerations and recommendation guide researchers on ethics associated with this technology.
When John Gurdon, a developmental biologist at Oxford University cloned frogs in 1960, he did it limitedly. Gurdon demonstrated that a nucleus from the intestinal lining cell of a tadpole is transferable to an enucleated fertilized egg. He found out that an adult cell’s nucleus could support progress up to the tadpole stage. However, he could not coax a nucleus from the cell of an adult amphibian. In the 1980s, researchers attempted to commercialize livestock cloning from nuclei extracted from fetuses and embryos. However, their efforts did not succeed because the cloned animals were unhealthy newborns that did not endure for long. Currently, cloning is partial to research and cloning humans would yield similar results. Moreover, using human and animal for research without the guarantee of positive results is ethically unwanted. Since survivability is as minimal as in animal cloning, it is unrecommended.
- Nisbet, M. C. (2004). Public opinion about stem cell research and human cloning. Public Opinion Quarterly, 68(1), 131-154. Retrieved from https://academic.oup.com/poq/article/68/1/131/1855075
- Roberts, R. J., Vincze, T., Posfai, J., & Macelis, D. (2014). REBASE—a database for DNA restriction and modification: enzymes, genes and genomes. Nucleic acids research, 43(D1), D298-D299. Retrieved from https://academic.oup.com/nar/article/43/D1/D298/2436339
- Shapiro, H. T. (1997). Ethical and policy issues of human cloning. Science, 277(5323), 195-196. Retrieved from http://science.sciencemag.org/content/277/5323/195.full
